ZyXEL Communications prestige p-2002 User Manual

P-2002 Series User’s Guide

98

Chapter 12 Troubleshooting

Table 39   Troubleshooting Telephone

There is no dial 

tone or I can’t make 

or receive calls.
or
There is beeping 

instead of the dial 

tone.

Check the telephone connections and telephone wire.
Beeping means that there is not a SIP account registered for the phone to use.
You can check the Prestige’s IP addresses and VoIP status in the Maintenance 

Status screen. 
Make sure you have the VoIP screen properly configured. If you configured a SIP 

account to receive calls on only one of the phone ports, make sure your phone is 

connected to that port.
Make sure you have the Phone Port screen properly configured. If you 

configured a phone port to only use one of the SIP accounts for outgoing calls,  

make sure that SIP account is properly configured and active (see the VoIP and 

Maintenance Status screens). 

There is a beep 

before the dial tone.

A single beep before the dial tone indicates that there is a voice message for SIP 

account 1.
Two beeps before the dial tone indicate that there is a voice message for SIP 

account 2.
Use your voice service provider’s instructions to check your voice messages.

Table 40   Troubleshooting Voice Service

After the VoIP is 

configured and 

working, others are 

unable to call you 

or you lose your 

connection during a 

call. There is a NAT 

router between the 

Prestige and the 

SIP server. 

This could be caused by a short NAT UDP session timeout on the NAT router. 

When the SIP session’s entry in the NAT table times out, the NAT router does not 

have any record to use for forwarding VoIP traffic to the Prestige.
If possible, set the NAT router to use a longer NAT UDP session timeout.
Otherwise, try one of the following:
•

Shorten the registration expiration period (see the Expiration Duration field 

in the VoIP Advanced screen) in order to cause the Prestige to re-register 

with the SIP register server more frequently. Note that this will not help if the 

SIP register server enforces a long registration expiration period (since the 

Prestige will also use the period set by the SIP register server).

•

Use STUN. If your VoIP service provider does not have a STUN server, you 

can still enable STUN and enter the IP address and port number of the SIP 

server in the STUN server fields. This causes the Prestige to send STUN 

requests to the SIP server. While this will not make STUN work (since there 

won’t be any responses to the STUN requests), it should keep the NAT UDP 

session in the NAT router.